Wetenschap - 7 november 2017

Peat bog emissions nullify what forests store

tekst:
Roelof Kleis

Dutch forests are only able to store a fraction of the total national CO2 emissions. What’s more, this is nullified by the emissions from the boggy wetlands.

© Wageningen University & Research

This sobering conclusion was drawn by Wageningen researchers and Statistics Netherlands (CBS) in the first Natural capital accounting of the Netherlands. In the report, which is still experimental, the balance sheet is drawn up of all known carbon stocks and flows in the Netherlands. The report was commissioned by the Ministry of Ministries of Economic Affairs and Infrastructure and the Environment as part of the project ‘Natural capital accounting in the Netherlands’.

Fossil fuel power stations
Carbon balance sheets are drawn up regularly. According to Lars Hein, professor of Ecosystem Services and Environmental Change, what is new about the Natural capital accounting is that the cycles of carbon within economy and the environment have been merged in a single review for the first time. This provides enlightening comparisons. For example, a single, large power station fuelled by coal emits as much CO2 as all bogs in the Netherlands joined.

A hectare of bogs emits as much CO2 as three households on average.
Lars Hein

Linking the data to ecosystems also yielded detailed maps of areas in the Netherlands that emit or store CO2. According to Hein, this spatial aspect is especially interesting for policymakers. They can now see down to the parcel level whether a piece of land is a source or a well of carbon. It brings the consequences of climate change very close. Hein: ‘A hectare of bogs, for example, emits as much CO2 as three households on average.’

Main culprit
Deeply dewatered bogs can even emit as much CO2 as eight households, Hein says. When it comes to ecosystems, the bog areas are the main culprits regarding CO2 emissions. Forests and other types of landscapes in the Netherlands store carbon, but the emissions of the peat bogs largely nullify that. The emissions of bogs are twice the amounts of the stock of all other ecosystems taken together.

Carbon stock in surface biomass. Source: Natural capital accounting, WUR/CBS report.
Carbon stock in surface biomass. Source: Natural capital accounting, WUR/CBS report.

The bog areas in Friesland and Drenthe in particular are responsible for the emissions. Due to the low groundwater levels, the peat oxidises in contact with air. Large amounts of CO2 are released during this ‘combustion’, although this is only a fraction (less than 4 percent) of what the Netherlands emits into the atmosphere. The total national emission is 195 megatons of CO2. Forests only store around 2 percent of this total.

Below ground stocks
Hein explains that a lot needs to change if we want to become climate neutral. ‘And this is not something we will accomplish by merely planting additional forests.’ Hein is a supporter of the cabinet’s proposal to store CO2 below ground. ‘Not on land, but in the sea. The oil companies have used the methods for years. They have been injecting CO2 in gas and oil fields to prolong production. A new aspect would be that this would now need to be done for periods that exceed a century.’

This is not something we will accomplish by merely planting additional forests.
Lars Hein

However, the real key to tackling the climate problem is in dealing with bogs in other parts of the world, says Hein. ‘Areas such as Indonesia, for example. There is 15 million hectares of bogs there, of which half has already been drained and is therefore degrading. If we want to remain below the 2 degrees of temperature rise, we will have to do something about that, by wetting the bogs and replanting the forests on them. Doing so is relatively cheap: it only costs about one tenth of afforestation here.’

According to Hein, the bogs in South-East Asia contribute about 5 to 6 percent of the global CO2 production. ‘Those are the places we really need to deal with on a global scale. The emissions of the bogs in Indonesia alone are more than one hundred times that of the Netherlands. Of course, we will still need to take care of the emissions of our own bogs as well.’


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